• Participant must have CLL or SLL (WHO criteria).

• Participant must require treatment according to iwCLL guidelines.

• Participants must have no prior systemic therapy for CLL or SLL, except:

‣ Prior local radiation for symptomatic disease is permitted.

⁃ Short course systemic corticosteroids is permissible for disease control, improvement of performance status, or non-cancer indication. However, duration of steroid course must be ≤14 days with maximum daily dose of ≤100 mg prednisone, ≤20 mg dexamethasone, or equivalent, and must be discontinued prior to study treatment (last dose may be administered up until the morning of / prior to study treatment). Inhaled steroids, topical steroids, and replacement / stress corticosteroids are permitted independent of above rules. In cases of autoimmune complications of CLL (e.g., ITP or AIHA), steroid usage is permitted.

• Age ≥18 years.

• ECOG performance status of 0, 1 or 2.

• Participants must meet the following organ and marrow function as defined below:

‣ absolute neutrophil count ≥1,000/µL without growth factor support (filgrastim within 5 days or PEGfilgrastim within 10 days of test), unless clearly due to disease under study (per investigator)

⁃ platelets ≥75,000/µL, or ≥20,000/µL if clearly due to disease under study (per investigator)

⁃ total bilirubin ≤2 x institutional upper limit of normal (ULN), or ≤3 x institutional ULN if due to Gilbert's syndrome, or with PI approval if clearly due to disease under study

⁃ AST(SGOT)/ALT(SGPT) ≤2.5 x × institutional ULN

⁃ CrCl or GFR ≥30 mL/min as estimated by the Cockcroft-Gault equation, the CKD-EPI equation, or as measured by 24-hour urine collection

• For females of childbearing potential, a serum pregnancy test must be negative within screening period.

• For female patients of childbearing potential: agreement to use highly effective form(s) of contraception (i.e., one that results in a low failure rate \[\<1% per year\] when used consistently and correctly) or remain abstinent (refrain from heterosexual intercourse) during the treatment period and to continue its use for ≥ 30 days after the last dose of zanubrutinib or ≥ 90 days after the last dose of sonrotoclax, and for ≥18 months fter the last dose of obinutuzumab (whicher is later).

‣ A woman is considered to be of childbearing potential if she is postmenarcheal, has not reached a postmenopausal state (\>12 continuous months of amenorrhea with no identified cause other than menopause), and is not permanently infertile due to surgery (i.e., removal of ovaries, fallopian tubes, and/or uterus) or another cause as determined by the investigator (e.g., Müllerian agenesis). The definition of childbearing potential may be adapted for alignment with local guidelines or regulations.

⁃ Examples of contraceptive methods with a failure rate of \< 1% per year include bilateral tubal ligation, male sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine devices. Hormonal contraceptive methods must be supplemented by a barrier method.

⁃ The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not acceptable methods of contraception.

• For men with a female partner of childbearing potential or a pregnant female partner: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom in addition to 1 of the highly effective methods of contraception listed below, from the time of taking the first dose of study drug , during the treatment period and to continue its use for ≥ 30 days after the last dose of zanubrutinib or ≥ 90 days after the last dose of sonrotoclax, and for ≥18 months fter the last dose of obinutuzumab (whicher is later).

⁃ -The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the patient. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not acceptable methods of contraception.

• Willingness to not donate or bank sperm or oocytes during the entire study treatment period and after treatment discontinuation for for ≥ 30 days after the last dose of zanubrutinib or ≥ 90 days after the last dose of sonrotoclax, and for ≥18 months fter the last dose of obinutuzumab (whicher is later).

• Ability to understand and the willingness to sign a written informed consent document. (Providing consents in as many languages as possible is encouraged)